The ISAS solar power satellite working group is working on a concept of an SPS strawman model for demonstration of electric power supply to customers at the earliest opportunity. The SPS is modularized, so that each unit can be launched by a commercial launcher to an equatorial low earth orbit where it is assembled automatically. The satellite can supply electric power by microwave to rectennas at every pass. Based on this model, technological and prograrnatic characteristics of a small SPS are discussed.